It is well-known in the art to provide an automotive vehicle with an internal combustion engine having a turbocharger including an exhaust driven turbine driving a compressor in the intake system to compress the charge and thereby increase the power obtainable from an engine of a particular displacement. Recently with the advent of emission controlling catalytic converters and other heat initiated exhaust treatment devices in the exhaust systems of spark ignition engine powered automobiles and certain other automotive vehicles, the application of turbocharged engines to such vehicles has resulted in the known combination of a turbocharged engine powered vehicle having a catalytic converter heat initiated exhaust treatment device in the exhaust system. The turbocharger turbine is conventionally provided with a wastegate valve actuated by suitable controls to limit the turbocharger boost pressure in the engine intake manifold to a predetermined maximum.
It has now been proposed that the converter equipped turbocharged engine exhaust system be provided with an additional bypass valve suitably positioned and controlled to bypass the engine exhaust gases around the turbine directly to the catalytic converter, or other heat initiated exhaust treatment device in the exhaust system, from the time of engine starting until the converter reaches a predetermined temperature at which it becomes operative. In this way, it is anticipated that the desired control of exhaust emissions by the converter will be established sooner and the overall exhaust emission levels may be more closely controlled. A disclosure of this concept and its application may be found in the copending United States patent application Ser. No. 25,337 filed Mar. 30, 1979 in the names of Jeff K. Lane, Joseph M. Negri and Donald J. Harrod and assigned to the assignee of the present invention.